1. Field of the Invention
The present invention relates to a fluid control valve for controlling fluid.
2. Description of Related Art
For example, wafer processing such as etching and thin film growth is made in a semiconductor manufacturing process. If foreign matters such as particle adheres to a wafer during the wafer processing, such foreign matters cause various problems; undesired impurities disperse on the wafer, pattern defect is caused by the foreign matters confined between the thin films, or expected electric characteristics can not be obtained due to the undesired impurities dispersing on silicon and insulated film. For preventing these problems, a cleaning process to remove foreign matters from the wafer without deteriorating is employed before the wafer processing.
In the cleaning process, foreign matters are dissolved and removed by means of chemical methods using chemical liquid such as a mixture of sulfuric acid and hydrogen peroxide, a mixture of ammonia and hydrogen peroxide, or a mixture of hydrochloric acid and hydrogen peroxide. A fluid control valve is adopted to supply such chemical liquid to the wafer. Hydrogen peroxide having a high effect of oxidizing is employed as chemical liquid. In recent years, the chemical liquid is supplied to the wafer at high temperature so as to supply the chemical liquid in an activated state to the wafer. As a result, a fluid control valve tends to be exposed to high corrosion atmosphere in many cases.
If a fluid control valve, which is exteriorly configured with a valve main body and a cylinder fixed by metal screws, is used in high corrosion atmosphere as above mentioned, the metal screws could be corroded failing to provide initial fastening strength. Therefore, a fluid control valve 1100 of Japanese Unexamined Patent Application No. 2002-022055A (shown in FIG. 16) for example is arranged without using metal screws.
FIG. 16 is a sectional view of the fluid control valve 1100 of JP2002-022055A.
The fluid control valve 1100 is designed metal-free and all the components except a compression spring 1101 are made of resin or rubber. The fluid control valve 1100 is exteriorly configured with a resin-made valve upper body (hereinafter, “upper body”) 1103 screwed up to a valve main body (hereinafter, “main body”) 1102. In the upper body 1103, cylinder 1104 and cover 1105 are screwed up together structuring piston chamber 1106. In the piston chamber 1106, piston 1107 is mounted to be movable. Piston rod 1108 of the piston 1107 protrudes downward through the cylinder 1104 into the main body 1102 and is connected with a diaphragm 1109. The piston 1107 is movable upward and downward to keep balance between an elastic force of the compression spring 1101 and pressure of operation fluid supplied from an operation port 1110. This up and down movement makes the diaphragm 1109 move into or out of contact with a valve seat 1111 provided in the main body 1102.